function [ output ]=sigma_cal(input)

%Environmental interference force
Tau1=0;
Tau2=0;
Tau3=0;

%Heavy vehicle
m11=646;
m22=837;
m33=155;
m23=0;
m32=0;
d11=303;
d22=425;
d33=74;
d23=0;
d32=0;


u_d_dot=input(1);
u=input(2);
v=input(3);
r=input(4);

sigma1=m22*v*r-d11*u-m11*u_d_dot+Tau1;
sigma2=-m11*u*r-d22*v+Tau2;
%sigma3=(m11-m22)*u*v-d33*r-m33*r_d_dot+Tau3;
output=[sigma1 sigma2];
